Tuning dial



Aug. 5., 1941.

E. E. KOHLS El' AL TUNNG DIAL,

Filed Feb. 16. 1938 2 Sheets-Sheet l gm@ ffm/5 5/57/7/7 5. 7770/27 pa,SM

gsm w Aug. 5, 1941. E. E. KoHLs Erm.

TUNING DIAL Filed Feb. 16, 1938 2 Smets-sheet 2 @an LN @www mim.

GOEE@ mm Patented Aug. 5, 1941 TUNING DIAL Erich Eugene Kohls and GlennS. Thompson, Fairy Chasm, Wis., assignors to Briggs & StrattonCorporation, Milwaukee, Wis., a corporation of Delaware .fipplicationFebruary 16, 1938; Serial No. 190,803

(Cl. lli-)` 2 Claims.

This invention relates to'improvements in radio tuning dials, and refersparticularly to .so-called automatic tuning for radio receivers wherebya receiver may be quickly and accurately tuned to any one of a number ofpredetermined different broadcasting stations.

Tuning devices of this character, except those which are driven byelectric motors, generally comprise a rotatable element directlyconnected with the condenser shaft and provided with a plurality ofstation selecting elements in the form of movable stops, each adapted toarrestmotion of the rotatable element at a deiinite point to tune thereceiver to a predetermined broadcasting station.

These individual station selecting elements or stops are adjustable topermit each one tc be used for one of a number of broadcasting stationslying in adjacent channels.

Heretofore the adjustment of these individual station selecting elementsor stops has been diflicult and required the services of an expert. Inaddition, their design was such that adjustment had to be made from inback of the panel or entailed at least partial dismantling of themechanism.

it is therefore an object of this invention to provide a radio tuningdevice of the so-called automatic type which is so designed thatadjustment of its individual station selecting elements or stops may bequickly and easily effected and does not require the services of anexpert.

Another object of this invention is to provide a tuning device of thecharacter described Wherein adjustment of the individual stationselecting elements may be effected entirely from in front of the paneland without the necessity for dismantling the mechanism.

A further object of this invention is to provide greater accuracy fortuning devices of the character described by improving the constructionof the individual station-selecting elements.

With the above and other objects in View which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed, and more particularly defined by the appended claims, itbeing understood that such changes in the precise embodiment of thehereindisclosed invention may be made as come Within the scope oftheclaims.

The accompanying drawings illustrate one complete example of thephysical embodiment of the invention constructed in accordance with v Ilwhich is joined to a large pulley i2 positioned the best mode so fardevised for the practical application of the principles thereof, and inwhich:

Figure 1 is a front plan view of a tuning device embodying thisinvention;

Figure 2 is a longitudinal sectional view through the tuning deviceillustrating its application to a radio receiver chassis;.

Figure 3 is a sectional view taken through Fig- -ure 2 on the plane ofthe line 3 3 with parts '.brokenaway;

ving drawings in which like numerals indicate like parts, the numeral 5designates the chassis of a radio receiver equipped with tuningcondensers 6 from which a condenser shaft l projects forwardiy towardthe panel 8 of the cabinet in which the receiver is mounted. The panelis provided with the customary opening to accommodate the dial assemblyindicated generally by the numeral 9. This assembly includes a glasscovered dial proper indicated by the numeral i0, which is assembled withthe condenser shaft and is equipped with the customary indicia andpointer for indicating the Wave length to which the receiver isadjusted.

Surrounding the dial l is an escutcheon ring in back of the panel. Aplurality of posts I3 riveted'to the pulley and having the escutcheonring xed thereto by screws M serves to join the ring to the pulley. Thepulley l2 has an arm vlli secured thereto by which it is mounted on thecondenser shaft l so as to turn with the shaft. A cable I6 trained overthe pulley l2 and a smaller pulley H which is driven by a knob I8,provides means for manually adjusting the condensers in the customarymanner.

Extending around substantially the lower half offthe escutcheon ring Ilare individual station selecting elements indicated generallynby thenumeral it. These station selecting elements have depressible buttons 2ton which the call letters of the various stations to be automaticallytuned are delineated. Depression of any one of these buttons renders`its station selecting element operative to arrest rotation of theescutcheon ring and consequently the condenser shaft at a predeterminedpoint necessary to tune the receiver to the broadcasting stationrepresented by the selected button.

Inasmuch as all of these station selecting elements are identical inconstruction, a description of one will suffice for all.

Each station selecting element consists of a body in the form of acylinder 2l having a large diameter` bore 22 at its outer end and asmall diameter` bore 23 at its inner end. Between the two bores is atapered bore 2d and between the large end of the tapered bore and thelarge diameter bore 22 are threads 25.

The inner end 25 of the cylinder is smaller in diameter than the centralportion 2'! of the cylinder, and its extreme outer end 28 is of adiameter even smaller than its inner end portion, to receive thecup-shaped button 2B. A spring snap ring 2? detachably holds the button2l) in position on the outer end of the cylinder.

At its extreme inner end the cylinder has an annular groove 39 toreceive a tongue 3| carried by a disk S2 from which an eccentricallydisposed stop finger 33 projects. The disk 32 is rigidly andnonrotatably secured to a stem 34 which passes through the central boresin the cylinder with substantial clearance between it and the smallestbore 23. This clearance, together with a gateway 35 which extends acrossthe flange left between the annular groove 3B and the inner end of thecylinder enables the disk and stem to be assembled with the cylinder.

This disk and stem constitute a movable dial carried stop whichcooperates with a stationary stop 3S to be hereinafter more fullydescribed, to limit rotation of the rotating unit at a definite pointwhich is adjustable by rotation of the stem and disk. The stem and diskare held in any desired position of rotational adjustment with respectto the cylinder 2i by a conical clamping bushing 3l pressed into thetapered bore 24 by a clamping screw 33 to grip the stem 34.

The manner of effecting this adjustment is clearly illustrated in Figure6 and to facilitate the same, a special tool 39 is provided. This toolconsists of a tube l equipped with a knurled knob 4l and an innerflattened end to engage in a screw slot SQ in the outer end of the screw38. A screw driver i3 inserted through the tube 46 is engageable in ascrew slot formed in the end of the stem 34.

Hence, by backing ofi the clamping screw to release the grip which theconical bushing has on the stem and holding the same in a releasedposition by means of the knurled knob lil, rotation may be readilyimparted to the stern Sli by means of the screw driver i3 to swing thestop pin 33 about the axis of the cylinder.

Before this adjustment can be made, it is of course understood that thecup-shaped button 20 is iirst removed.

The entire station selecting element or movable stop is mounted inposition by means of two complementary ring members lll and 45 in such amanner as to permit endwise or axial depression of the assembly todispose its stop pin 33 in line with the stationary stop 35. Both ofthese ring members lill and may be formed of bendable metal and each hasa flange 46 by which it is attached to the back or" the escutcheon ringand a cylindrical part Lil, the outer edge of which carries a flange el?parallel to and directed in the opposite direction of the flange 46.

Together, the two complementary ring members form a box-like annularchannel which encloses the several individual station selectingelements. The inner ring member M is permanently secured to theescutcheon ring ll by having its flange 46 spot-welded to the back ofthe escutcheon ring, but for purposes of assembly the other ring member45 is held to the escutcheon plate by having its ange 46 interposedbetween the back of the escutcheon ring and the adjacent posts I3.

The adjacent edges of the anges G8 of both ring members havesemi-circular notches 5i), each pair of which forms a round hole toreceive the end portion 2S of a cylinder 2l. The engagement of the endportion 25 in the hole thus formed together with tongue and grooveconnections 5I between the cylindrical portions 4l of the two ringmembers and the enlarged central portion 2'! of the cylinder guides thecylinder for endwise motion and accurately holds the same againstrotation.

A compression spring 53 coniined between the shoulder formed at thejuncture of the inner and central portions 26 and 2l' of the cylinderand the inner surfaces of the flanges i8 of the ring members yieldinglyurges the cylinder 2i toward the escutcheon plate. This spring propelledmotion of the cylinder El is limited by the engagement of the front endof its central portion 2l with the end of a rearwardly directed tubularpart Effi encircling a hole 55 in the escutcheon plate through which thebutton 2@ projects.

In this manner the cylinder 2i and consequently the movable stop isyieldingly held in an inoperative position at which the stop pin 33clears the stationary stop 33 to be instantly ready for movement tooperative position by merely an inward depression.

The stationary stop 3E, in order to accommodate the thickness of thestop pins 33 and insure accuracy in the location of the position atwhich rotation of the tuning condensers is arrested regardless of thedirection from which the selected movable stop is moved toward thestationary stop, has a degree of lost motion. To this end the stationarystop is pivot-ed from the condenser shaft and is held in place with adegree of lost motion by a screw 55 carried by a fixed support 5l andengaging a transverse slot E3 in the stop.

The length of the transverse slot 53 is such to permit the lower freeend of the stop 36 to move just the required distance necessary toarrest adjusting motion of the escutcheon ring at the saine positionregardless of the direction from which the selected movable stopapproached the stationary stop.

In assembling, the individual station'sclecting elements, each properlyassembled, are first applied to the escutcheon ring before the ringmember 'i5 is in place. This assembly is easily eiected especially ifthe buttons Eil are left oi the individual station selecting elements`Then, after all of the individual station selecting elements have beenapplied in this manner and with all of their pins positioned to pointinwardly toward thel center, the other ring member 5 may be assembledwith the escutcheon ring.

From the foregoing description taken in connection with the accompanyingdrawings, it will be readily apparent to those skilled in the art thatthis invention provides an automatic tuning device for radio receiverswhich greatly facilitates adjustment of the individual station selectingstops; and that this adjustment may be entirely effected from in frontof the dial and. does not require any great degree of skill.

What We claim as our invention is:

1. In a radio tuning device of the character described: a rotatableescutcheon ring; a plurality of depressible stop devices carried by theescutcheon ring, each of said stop devices comprising a longitudinallymovable supporting member, and a stop pin adjustably carried thereby;and means for mounting the supporting members of all of the stop devicesfrom the escutcheon ring comprising, radially spaced ring members, andtongues carried by each of said ring members and slidably disposed ingrooves in said supporting members.

2. In a radio tuning device: a rotatable escutcheon ring adapted uponrotation to effect tuning of a receiver with which the device isassociated; means for arresting tuning motion of the escutcheon ringincluding depressible stop devices carried by the escutcheon ring; eachof said stop devices comprising a supporting body and a stop pina-djustably carried thereby; vand. means for slidably but nonrotatablysupporting said body members from the escutcheon ring including radiallyspaced ring members fixed to-

